The singer was carried backstage to recover and the band had to halt the gig until he felt better.

A video featuring the Canadian star in pain has been posted online, showing him writhing around the floor in discomfort and telling his bandmates, “My knees were quivering and I couldn’t stand… I don’t know what happened, I never had that feeling.”

It is still not clear why Whibley fell to his knees, but the scare won’t end the tour. Sum 41 will continue their Japanese trek with shows in Fukuoka, Osaka and Tokyo this week.